The present invention relates to an antenna and a manufacturing method therefor. Particularly, the present invention relates to an antenna and a manufacturing method therefor, in which the sensitivity characteristic of the dual band antenna utilizing a plurality of frequency bands is improved, and at the same time, the antenna can be miniaturized.
The generally known CDMA mobile communication terminal having a plurality of frequency bands is capable of transmitting and receiving voices and motion pictures. The dual mode antenna which is used in such a CDMA terminal has to be capable receiving signals through a plurality of frequency bands.
In this dual band antenna, a contacting-separating type antenna and a vertical antenna are coupled together, or a linear monopole antenna and a vertical antenna are coupled together. Or primary and secondary antennas are coupled together in a serial or parallel form.
One of this conventional vertical dual band antennas is disclosed in Japanese Patent Application Laid-open No. Hei-10-322122.
This dual band antenna is constituted a shown in FIG. 1. That is, there is formed a primary coil 10 which has a certain length and pitches. Further, a secondary coil 30 which has a length and pitches larger that those of the primary coil 10 is vertically connected to the lower end of the primary coil 10, thereby forming a dual band antenna 40.
In this antenna 40, a frequency band is provided over the entire primary and secondary coils 10 and 30, while another frequency band is provided in the secondary coil 30 which has a length and pitches larger than those of the primary coil 10.
In this antenna 40, however, the primary coil 10 and the secondary coil 30 are connected in the vertical direction, and therefore, the overall length of the antenna is extended, with the result that the miniaturization of the mobile communication terminal becomes difficult.
Meanwhile, in an attempt to overcome the above described disadvantages, recently the antenna is installed within the terminal, and when the terminal is used, the antenna is drawn out. In this method, however, an antenna accommodating space has to be provided within the terminal, and therefore, the mobile communication terminal cannot be miniaturized.
The present invention is intended to overcome the above described disadvantages of the conventional techniques.
Therefore it is an object of the present invention to provide an antenna in which the dual band antenna capable of receiving signals through a plurality of frequency bands is improved in its sensitivity characteristic, and the antenna can be miniaturized.
It is another object of the present invention to provide a manufacturing method for an antenna, in which the desired dielectric constant can be obtained by arbitrarily selecting the dielectric material so as to minimize the designing limitation, and the conductive line of the antenna can be constituted in an accurate manner so as to minimize the generation of defects during the manufacture.
In achieving the above objects, the antenna according to the present invention includes: a spiral primary coil; and a spiral secondary coil connected to one end of the primary coil, disposed outside the primary coil, and having pitches larger than those of the primary coil, whereby a frequency band is provided over the entire primary and secondary coils, and another frequency band is provided in the secondary coil.
In another aspect of the present invention, the method for manufacturing an antenna according to the present invention includes the steps of: forming a first cylindrical body; forming a first securing spiral channel around the first cylindrical body starting from an end of the first body to a certain part of the first body and having a predetermined length and pitches; installing a primary coil through the first securing spiral channel; forming a second cylindrical body having an inside diameter same as or larger than an outside diameter of the cylindrical first body, so as to receive the first cylindrical body; forming a second securing spiral channel around the second cylindrical body starting from an end of the second cylindrical body to a certain part of the second cylindrical body and having a predetermined length and pitches; installing a secondary coil through the second securing spiral channel; and inserting the first cylindrical body into the second cylindrical body, and contacting a portion of the exposed secondary coil of the second cylindrical body to a portion of the exposed primary coil of the first cylindrical body.
In still another aspect of the present invention, the method for manufacturing an antenna according to the present invention includes the steps of: i) preparing inner and outer ceramic substrates; ii) forming a via hole in each of the inner and outer ceramic substrates, and filling a conductive paste in the via hole; iii) forming a primary coil pattern on a surface of the inner ceramic substrate by using an antenna pattern forming means; iv) forming a secondary coil pattern on a surface of each of the outer ceramic substrates by using an antenna pattern forming means; v) bonding the inner and outer substrates together with the inner substrate having the primary coil disposed between upper and lower sheets of the outer substrates having the secondary coils, so as to make the primary and secondary coils connected together in a spiral form through the via holes of the inner and outer substrates; and vi) cutting the substrates thus bonded together into individual antennas.
In still another aspect of the present invention, the method for manufacturing an antenna according to the present invention includes the steps of: i) preparing green sheets consisting of inner and outer ceramic substrates; ii) forming via holes in each of the inner and outer ceramic substrates of the green sheet, and spreading a conductive pattern in each of the via holes; iii) forming primary coil patterns on a surface of each of the inner ceramic substrates by using an antenna pattern forming means; iv) forming secondary coil patterns on a surface of each of the outer ceramic substrates by using an antenna pattern forming means; v) stacking the inner substrates with the primary coils formed thereon between upper and lower sheets of the outer substrates with the secondary coils formed thereon so as to make the via holes of the inner and outer substrates aligned; vi) cutting the stacked structure into individual antennas; and vii) baking the inner and outer substrates of the stacked structure with the primary and secondary coils formed thereon at a predetermined temperature so as to complete the antenna.
In still another aspect of the present invention, the method for manufacturing an antenna according to the present invention includes the steps of: i) preparing a plurality of flexible substrates; ii) forming a diagonal conductive pattern on a first flexible substrate of the plurality of the flexible substrates; iii) forming a plurality of inclined conductive patterns on a surface of a second flexible substrate of the plurality of the flexible substrates at predetermined gaps; iv) winding the first flexible substrate around a cylindrical support; and v) winding the second flexible substrate around the first flexible substrate.